Thermostatic material



Dec. 13, 1927. I

' V. G. VAUGHAN THERMOSTATIC MATERIAL Filed Feb. 27. 1925 I 6 0 700 TemperaTur-e in degrees Cenfigrade l I I 300 400 500 G mQU commcmixm EKGP INVENTOR V/c/or 6f Vauyfiaa BY I WITNESSES- ATTORNEY Patented Dec. 13, 1927.

UNITED STATES PATENT OFFICE.

vIc'ron a. vacuum, or nasr rrr'rsnunen, rnunsvrvmm, assrenon ro was'rmonousn ELECTRIC a nanuracruame comramr, A coarona'rron or TENN- SYLVAN IA.

rnnamosrarro MATERIAL.

Application filed February 27, 1925. semi No. 12,042.

My invention relates to temperature'lcom trolled devices and particularly to thermostats and thermostatic material.

One obiect of my invention is to provide a bimeta lie thermostat, the elements. of which shall have a relatively large difference between their respective temperature coeflicients of expansion and that shall be composed of material capable of being subjected to relatively high temperatures.

In racticing my invention, I provide a metallic thermostatic element comprising a plurality of metals, one of which is an alloy comprising cobalt and chromium.

e single figure of the drawings illustrates two curves showing the temperature coeflicients of expansion of two metallic elements" which I prefer to employ in my thermostat. X

A number of metals that may be employed in thermostatic members for use with relatively low tem erat-ures are well known, such as iron and rass. However, when such metals are employed for relatively high temperatures they soon lose their original operating characteristics and fail to respond to changes of temperature, and the device therefore becomes useless. I have found that an alloy containing cobalt and, chromium in varying proportions, and known as stellite,

may be employed as one of the metallic elements in a bimetallic thermostat.

. The proportion of chromium and of cobalt employed in the alloy, may vary, as for inas stance, I may employ 80% of cobalt and 20% of chromium, or I may employ 55% of cobalt and slightly over 40% of chromium, together with smaller rcentages of tungsten, and'of carbon. Wh le alloys containing. difierent .40 percentages may vary somewhat in their operation, thevariations will not be suflicient to revent their use in'thermostatic devices.

curve designated by the numeral 11 illustrates the temperature coefiicients of expansion of a cobalt chromium alloy compris mg substantially of cobalt, 40% of chromium, with small percentages of tungsten and of other metals,'between the temratu're limits of zero and approximately m c. I

I A curve 12 illustrates the temperature coefficients of expansion of a nickel steel alloy containing approximately 42% of nickel. The nickel steel alloy hasa very much lower temperature coefiicient of expansion at temperaturesfrom substantially zero to 300 0., after which its temperature coeflicient of expansion increases and becomes but slightly less than that of the cobalt chromium alloy. Where the temperature range of from substantially zero to 300= C. is to be controlled it will be possible, therefore, to obtain relatively lar e deflections of .a thermostatic element wl iich comprises a cobalt-chromium alloy and a 42% nickel-steel alloy suitably secured together in a manner well known in the art. I

While I have shown a curve of expansion coeflicients having nickel steel alloy as the low expansion member of a thermostatic element, I do not desire to be limited thereto, as my invention relates more particularly to the use of the cobalt-chromium alloy and it is evident that it-may be employed with any other suitable alloy expansion metal with which it can be properly united in grder to provide the usual bimetallic mem- Various modifications and changes may be made without departing from the spirit and scope of the invention, and I desire therefore that only such limitations shall be placed thereon as are imposed by the prior art.

I claim as my invention:

1. A heat responsive device consisting of two metallic elements, one of said elements being an alloy containing cobalt andchromium, the percentage ofcobalt being 1n excess ofthe'percentage of chromium and the other element being a nickel steel alloy 2.:A heat responsive device comprising metallic elements,-one of said elements being an alloy of cobalt and chromium and the other element being nickel steel.

- 3. A heat responsive 'device comprising metallic elements, one of said elements being an allo ofcobalt and chromium and the other ement being a reversible nickel steel.

4.- A heat-responsive device comprising two metallic elements, one of said elements being an allo containing cobalt, and the other element eing a nickel steel alloy.

5. A heat-responsive device comprising 5 two metallic elements having relatively different temperature coefficients of expansion,

the element having the higher coefiicient being an alloy1 of cobalt and chromium, and v the element aving the lower coefiicient being an alloy of nickel steel.

In testimony whereof, I have hereunto subscribed my name this 14th day of February, 1925. I VICTOR G. VAUGHAN. 

